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Lambda-CDM theory - Woo or not?

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Tubbythin said:
Erm. You do realise "zero point energy" and "vacuum energy" are often used as synonyms?
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Sure, but one label is a scientifically accurate label and the other is not. There is no energy at a "zero point", and there is no vacuum that actually achieves a "zero state" of energy. Every vacuum has energy (and pressure) in it at all times. There is always energy in the vacuum.
 
Ziggurat said:
Yes, those ones. Now, try actually consulting one of those textbooks. Look in the index for the word "pressure". Find the first instance of a reference to pressure. You will likely find that they define the term when they first use it.
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http://en.wikipedia.org/wiki/Pressure

You'll PV=nRT there too. :)

The problem is that "pressure" is typically defined as:

146ffa227c9c02a846c1bd67cb6c537c.png


and you are *IGNORING* the force on the outside of the plates.
 
Michael Mozina said:
Sure, but one label is a scientifically accurate label and the other is not. There is no energy at a "zero point", and there is no vacuum that actually achieves a "zero state" of energy. Every vacuum has energy (and pressure) in it at all times. There is always energy in the vacuum.
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They are both scientifically accurate labels. The "zero" does not apply to the energy - it is "zero point" energy, i.e. the energy of the zero point. It is not zero energy.
 
It's amazing......

I had no idea at the start of this conversation how truly "lost" you folks are when it come to actual physical processes and pure physics. You can't tell the difference between "negative" and "less than", and when it comes to the actual physical processes that produce "pressure" you're absolutely clueless.

I guess if all one understands is math, your belief in "negative pressure" probably makes some sense. You evidently all do believe that just because there is a minus sign in that one math formula, that automatically means there is "negative" pressure in that chamber. In fact the entire chamber is filled with atoms and pressure galore, not to mention QM forces that put "pressure" on every side of every plate.

I really believed at one time that I might be able to convince a creationist that their beliefs were not "scientifically viable", or "empirically supported", but I learned after awhile that denial can be a very powerful thing. It doesn't seem to matter one iota to any of you that you can't demonstrate inflation actually existed, or that dark energy actually exists in nature, or that SUSY particles are real. None of it matters to you folks. All that matters is your math, and physics be damned.

It seems to me that this whole fixation on negative pressure in a vacuum is a predominately convenient distraction from the actual thread, but it also highlights an important problem with your industry. You folks *only* understand math. You clearly have no clue about actual physics or the physical processes that your math relates to. Evidently not a single one of you can distinguish between "negative pressure" and "lower pressure" because you beloved math formula has a minus sign in it, and you know absolutely nothing at all about QM or particle physics. Even with diagrams and links to additional physical descriptions of what occurs at the level of QM, your denial routine continues. This is so typical of discussions with creationists. The moment their show is busted they get all hostile and uptight and eventually just wallow in pure denial.

Deny it all you like, but the pressure from the outside is what "pushes" the plates together. That is why Wiki's diagram has bigger arrows on the outside of the plates pushing them together, and smaller ones pushing them apart.

300px-Casimir_plates.svg.png


As the link states:
http://physicsworld.com/cws/article/news/32380

The result is that the total field inside a gap between conductors cannot produce enough pressure to match that from outside, so the surfaces are pushed together.
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That person understands the actual "physics" of what occurs at the level of QM whereas the rest of you are utterly and completely clueless and you are in pure denial.
 
Michael Mozina said:
http://en.wikipedia.org/wiki/Pressure

You'll PV=nRT there too. :)

The problem is that "pressure" is typically defined as:

[qimg]http://upload.wikimedia.org/math/1/4/6/146ffa227c9c02a846c1bd67cb6c537c.png[/qimg]

and you are *IGNORING* the force on the outside of the plates.
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Again with the wikipedia? I thought you were using textbooks.

The reason we're insisting on using p = -dE/dV is that (if E is computed correctly, closed system, etc.) then this *is* the force on the plates---not "the force on the outside", nor "the force on the inside", but the actual net force which is what you actually measure in an experiment.
 
Reality Check said:
They are both scientifically accurate labels. The "zero" does not apply to the energy - it is "zero point" energy, i.e. the energy of the zero point. It is not zero energy.
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Nah. The term "zero point energy" is an oxymoron. If it was a true "zero point" it would have no energy. Since no vacuum can be achieve a "zero state", it is irrational to call it "zero point energy". It's just "preexisting energy" that flows through every vacuum. The term "vacuum energy" is a meaningful and useful label, whereas the term "zero point energy" is not.
 
Michael Mozina said:
http://en.wikipedia.org/wiki/Pressure

You'll PV=nRT there too. :)
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Yes: as an example equation of state, not as a definition. And not even the correct one for real gasses.

The problem is that "pressure" is typically defined as:

[qimg]http://upload.wikimedia.org/math/1/4/6/146ffa227c9c02a846c1bd67cb6c537c.png[/qimg]
Click to expand...

Why do you say "pressure" and not simply pressure? Are you implying that it's not real pressure being defined, but only something people label as pressure?

In any case, it's amazing how long it's taken you to write down a simple definition of pressure.

Now, this may take a little bit of math, something you don't seem to approve of much, but do you understand the connection between P=F/A and [latex]$P=-\frac{\partial E}{\partial V}$[/latex]? I can go through it if you want, but it's important to understand why they're completely equivalent definitions before we proceed.

and you are *IGNORING* the force on the outside of the plates.
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No, actually, I'm not. But that's actually irrelevant to my point anyways, though I don't expect you to understand why at this stage. Baby steps, Michael, baby steps. It's taken this long to get to P=F/A, can't expect you to get much farther in the same post.
 
ben m said:
Again with the wikipedia? I thought you were using textbooks.

The reason we're insisting on using p = -dE/dV is that (if E is computed correctly, closed system, etc.) then this *is* the force on the plates---not "the force on the outside", nor "the force on the inside", but the actual net force which is what you actually measure in an experiment.
Click to expand...

The "net force" as you call it in no way supports your claim that this process is an example of "negative pressure in a vacuum". There is no such thing. The very best you might ever achieve is "zero pressure" on any surface. In the real world however there is "pressure" on every side of every plate and a "pressure difference" between the outside and the inside.
 
Michael Mozina said:
They already know it's there. Harnessing it is something else altogether.



It's not "lower than zero", it "lower than the outside (of the plates) pressure, and *greater than zero*.

Hell, even when I provide you folks to links that agree with my explanation, diagrams that agree with my explanation and the whole nine yards, you all sit around in pure denial of simple fact. The very "best" vacuum on Earth contains atoms in it. The very best vacuum on Earth therefore has a "pressure" that is "greater than" zero. The best vacuums on Earth contain all sort of neutrinos and flowing energy in them. There is never any area of any vacuum that contains "zero" pressure, so there is no way you will ever get "less than" zero pressure inside a chamber that has pressure in it. This whole discussion amounts to pure denial on your part since the whole thing takes place in a positive pressure environment.
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Again that should be very easy for you to demonstrate, by measuring your always “positive pressure environment”.
 
Michael Mozina said:
Nah. The term "zero point energy" is an oxymoron. If it was a true "zero point" it would have no energy. Since no vacuum can be achieve a "zero state", it is irrational to call it "zero point energy". It's just "preexisting energy" that flows through every vacuum. The term "vacuum energy" is a meaningful and useful label, whereas the term "zero point energy" is not.
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MM: Zero point is the ground state of a system. A vacuum is a ground state. A ground state can have energy. Zero point energy is the energy of a zero point = energy of a ground state = energy of a vacuum.

"preexisting energy" is not quite right. Vacuum/ground state/zero point energy does not preexist. It comes into existence momentarily as virtual particles are created and destroyed. Perhaps you meant the expectation value of the zero point energy?
 
Michael Mozina said:
Sure, but one label is a scientifically accurate label and the other is not. There is no energy at a "zero point", and there is no vacuum that actually achieves a "zero state" of energy. Every vacuum has energy (and pressure) in it at all times. There is always energy in the vacuum.
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A quote:
Although the Casimir effect can be expressed in terms of virtual particles interacting with the objects, it is best described and more easily calculated in terms of the zero-point energy of a quantized field in the intervening space between the objects.
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Michael, do you agree that this quote is in direct conflict with what you are saying? Do you know where this quote has come from?
 
Michael Mozina said:
The "net force" as you call it in no way supports your claim that this process is an example of "negative pressure in a vacuum". There is no such thing. The very best you might ever achieve is "zero pressure" on any surface. In the real world however there is "pressure" on every side of every plate and a "pressure difference" between the outside and the inside.
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Michael, agree or disagree...
"P=-dE/dV is a text book definition of pressure"?
 
Ziggurat said:
No, actually, I'm not. But that's actually irrelevant to my point anyways, though I don't expect you to understand why at this stage. Baby steps, Michael, baby steps. It's taken this long to get to P=F/A, can't expect you to get much farther in the same post.
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Zig, it stills comes back to exactly the same issue. The pressure on the outside of the plates is "greater than" the pressure between them. No area of the chamber experiences "negative pressure". The rest of this nonsense is just "posturing" on your part. You're confused by your own math evidently.

The Casimir effect is *not* an example of "negative pressure" in a vacuum. It's an example of a "pressure difference" between the outside and inside of the plates. Period.
 
Michael Mozina said:
Nah. The term "zero point energy" is an oxymoron. If it was a true "zero point" it would have no energy.
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Wrong. To quote from wiki: "In physics, the zero-point energy is the lowest possible energy that a quantum mechanical physical system may have and is the energy of the ground state. "

Since no vacuum can be achieve a "zero state", it is irrational to call it "zero point energy".
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Not if the zero point is the lowest possible state of a QM system it isn't.

It's just "preexisting energy" that flows through every vacuum. The term "vacuum energy" is a meaningful and useful label, whereas the term "zero point energy" is not.
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When did you become arbiter of usefullness?
 
Reality Check said:
MM: Zero point is the ground state of a system.
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Yes, I'm aware of the fact it is used interchangeably with "vacuum energy". I just personally think it's a misleading term. There is "energy flowing" through the system at all times. It never achieves a "zero point", so why call it a "zero point"? Ground state energy might make sense, but "zero point energy" does not.
 
Michael Mozina said:
Yes, I'm aware of the fact it is used interchangeably with "vacuum energy". I just personally think it's a misleading term. There is "energy flowing" through the system at all times. It never achieves a "zero point", so why call it a "zero point"? Ground state energy might make sense, but "zero point energy" does not.
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It only doesn't make sense if you don't know what you're talking about imho.
 
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